The muscularis externa consists of smooth
muscle fibers arranged into two layers. The layer of circular muscle
fibers (cut in longitudinal section) appears at the upper left, while the
layer of longitudinal muscle fibers (cut in cross section) appears at lower
right.

In between the two layers of muscle lies the parasympathetic nerve
plexus of Auerbach (also called the myenteric plexus). In routine
histological specimens, the ganglia (small clusters of nerve cell bodies)
are the only noticeable feature of Auerbach's plexus.

Nerve
cell bodies are usually rather conspicuous. Each cell body can
be quite large (up to ~50µm), with relatively basophilic cytoplasm,
with a large round euchromatic nucleus, and with a single prominent nucleolus.

Associated
with peripheral ganglia are numerous small satellite cells and Schwann cells,
as well as fibroblasts of the surrounding connective tissue.